It is well known in the art that wastewater can be collected into a separator tank to remove debris. Separator tanks have long been used to separate oils from water. Generally, these debris or oils may be called contaminants.
The use of separator tanks poses two problems when used to treat waste water. One, high flow rates create turbulence. The turbulence diminishes the ability of separator tanks to separate the contaminants. The turbulence may also re-mobilize the already separated contaminants, placing the contaminants back into the waste water to be treated. To avoid these undesired effects, the separator tanks must be made significantly large to overcome the effects of turbulence. Second, the separator tanks must be made large enough to perform during peaks in flow. Peaks in flow mean higher flow rates, causing two effects which impact the total amount of contaminants contained in these flows. First, the high flow rate brings a higher volume of liquid and overall more contaminants. Second, the high flow rate has increased contaminant carrying capacity owing to the higher flow rate itself. These two factors, combined, would result in greater total contaminants being brought to the separator tank during peak flows. This phenomenon is particularly apparent with treatment of storm water runoff, where the initial storm water contains the bulk of the contaminants, being the “first flush” of the drainage area. However, there is a limit to the total amount of contaminants available. Even though the high flow rates are capable of carrying and remobilizing a greater amount of contaminants, the drainage area has already been washed by the initial flush of storm water. After this initial flush of storm water, the separator tank then experiences relatively high flow of water that is relatively free of contaminants. If the separator tank is too small, these high flows will remobilize the already separated contaminants. Again, the separator tanks must be designed to be large enough so that these peak high volumes and flow rate do not remobilize the contaminants.
The large size requirements for separator tanks limit their usefulness to treat liquids of variable or high flow. Many attempts have been made to reduce the size requirements of the separator tank.
Of note, U.S. Pat. No. 4,578,188 to Cousino teaches a method to allow low flow to fall into a separator tank or other disposal and high flow to jump across a gap. The gap is contained within a weir such that extremely high flow completely bypasses the gap. Presumably, the low flow will spill into the settlement tank along with its carried contaminants while the high flow has enough kinetic energy to continue on.
U.S. Pat. No. 4,985,148 to Monteith teaches a nearly identical and simplified method to achieve a similar result. Monteith dispenses with the gap but continues to use the weir, dumping all low flow into an integrated separator tank. As the separator tank fills, the separated water in the separator tank exits downstream of the weir. Monteith teaches a way to house the weir, separator tank, and return from separator tank all in a single container.